1. Field of the Invention
The present invention relates to a substrate processing method and a substrate processing apparatus each for performing coating processing of, for example, a resist solution, developing processing, and the like for a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display, or the like.
2. Description of the Related Art
In the photolithography technology in processes of semiconductor device fabrication, a resist is applied to the front face of a semiconductor wafer (hereinafter, referred to as a xe2x80x9cwaferxe2x80x9d), the applied resist is subjected to exposure processing into a predetermined pattern and further to developing processing, thereby forming a resist film in the predetermined pattern. Such a series of processing is performed by a system in which an aligner is connected to a coating/developing apparatus.
FIG. 17 is a plan view showing an example of the above-described system, in which a cassette C housing therein substrates, for example, 25 wafers W is carried into a cassette stage 1 in a cassette station A1. A processing station A2 is connected to the cassette station A1, and further an aligner not shown is connected to the processing station A2 through an interface station A3.
A wafer W in the cassette station C on the cassette stage 1 is taken out by a transfer arm 11 and sent via a transfer unit of a shelf unit 12 to a coating unit 13, where a resist is applied thereto. Thereafter, the wafer W is transported via a wafer transporter MA, a transfer unit of a shelf unit 14, the interface station A3, to the aligner to be exposed to light. The wafer W after the exposure is transported via a reverse route to the processing station A2, and developed in a developing unit not shown provided at the tier under the coating unit 13, and thereafter the wafer W is transported via the wafer transporter MA, the transfer unit of the shelf unit 12 to the cassette C.
It should be noted that shelves of the shelf units 12 and 14 are configured as a heating unit, a cooling unit, a transfer unit for the wafer W, a hydrophobing unit and the like, so that heat processing and cooling processing are performed in this order in the shelf units 12 and 14 before the coating with the resist and before the developing processing for performance of the coating with the resist or the like at a predetermined temperature. Incidentally, numeral 15 denotes a transfer arm for transferring the wafer W between the processing station A2 and the aligner.
It is well known that organic substances adhere to the wafer W in a clean room atmosphere, the organic substances causing occurrence of flaking-off of the resist and coating particles, and thus there has been a great demand for removal of such organic substances. For the demand, it is more typical to clean the wafer W to thereby remove the organic substances, but the cleaning by a solution is often improper depending on the kind of films. Thus, the present inventor has developed a technique of removing the organic substances by irradiating the wafer W with an ultraviolet ray.
What is well known as the above-described UV cleaning apparatus is, for example, the configuration in which the wafer W on the mounting table is irradiated with the ultraviolet ray by a UV lamp for a predetermined period of time in a processing chamber of an atmosphere of natural air or an oxygen-rich atmosphere in a processing chamber. When this cleaning apparatus is installed into the aforesaid system, it is conceivable to dispose the apparatus, for example, in the shelf unit 12 or 14, and to transport the wafer W via the cassette C on the cassette stage 1, the transfer unit of the shelf unit 12, the cleaning apparatus, the hydrophobing unit, to the coating unit.
The cleaning apparatus, however, has a poor cleaning efficiency because of existence of gasses such as water vapor and oxygen which absorb the ultraviolet rays in the processing chamber, and thus it requires a period of cleaning, for example, 60 seconds to remove, to a predetermined amount or less, the organic substances adhering to the wafer W. Thus, the installation of the apparatus into the aforesaid coating and developing apparatus increases a period of time of the wafer W waiting for transport in the other units, whereby throughput is susceptible to deterioration. It is conceivable to increase the irradiation energy of the UV lamp in this event, but the power consumption also increases, presenting a problem in cost.
An object of the present invention is to provide a substrate processing method for removing deposits on a substrate in a short period of cleaning to improve coating properties of a resist solution and an apparatus therefor.
Thus, a substrate processing method of the present invention is characterized by comprising the steps of:
irradiating a front face of a substrate with a light from a light source to thereby remove a deposit on the front face of the substrate; subsequently, coating the front face of the substrate with a resist solution;
performing exposure processing for the substrate which has been coated with the resist solution; and
performing developing processing for the substrate after the exposure to obtain a resist pattern, wherein the step of removing the deposit on the front face of the substrate is performed while a gas absorbing no light is being introduced into a light irradiation space between the light source and the substrate. In this event, the light irradiated onto the front face of the substrate comprises an ultraviolet ray, and the gas absorbing no light comprises an inert gas.
In the above-described method, the front face of the substrate is irradiated with light, so that the deposits such as organic substances adhering to the substrate, for example, in a clean room atmosphere can be removed, resulting in improved coating properties of the resist solution. In this event, the gas absorbing no light is introduced into the light irradiation space between the light source and the substrate, thereby improving irradiation efficiency of the light, shortening the period of cleaning, and preventing oxidation of the substrate.
It is suitable to perform the step of supplying a hydrophobic processing gas to the front face of the substrate to perform hydrophobic processing for the front face between the step of removing the deposit on the front face of the substrate and the step of coating the front face of the substrate with the resist solution, and in this case the quality of the front face of the substrate is improved by the irradiation with light, resulting in improved coating properties of the hydrophobic processing gas in the hydrophobic processing.
The above-described substrate processing method is carried out in a substrate processing apparatus comprising: a cleaning and hydrophobing unit including a cleaning unit, having a light source for irradiating a substrate with a light and a gas supplier for introducing gas absorbing no light into a light irradiation space between the light source and the substrate, for irradiating the front face of the substrate with the light from the light source to thereby remove a deposit on the front face of the substrate, and a hydrophobing unit for supplying a hydrophobic processing gas to the front face of the substrate to perform hydrophobic processing for the front face; a coater for coating the front face of the substrate with a resist solution; and a developer for performing developing processing for the substrate which has been coated with the resist solution and subjected to exposure processing to obtain a resist pattern.
For example, the unit including the cleaning unit and the hydrophobing unit here comprises: a processing container including a mounting table for holding the substrate; a light source for irradiating the substrate held on the mounting table with the light; a hydrophobic processing gas supplier for supplying the hydrophobic processing gas to the substrate held on the mounting table; and the gas supplier for introducing the gas absorbing no light into the light irradiation space between the light source and the substrate, wherein the front face of the substrate is irradiated with the light from the light source while the gas absorbing no light is being introduced into the irradiation space, and subsequently the hydrophobic processing gas is supplied to the front face of the substrate.
Further, a substrate transporter for transporting the substrate between the cleaning unit and the hydrophobing unit may be provided, and in the case where the cleaning unit and the hydrophobing unit are provided in the same processing chamber, the apparatus can be downsized.
Further the cleaning unit and the hydrophobing unit may be provided in different processing chambers, and a transporter may transport the substrate between the cleaning unit and the hydrophobing unit through an exclusive transport path.
These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.